Atomic Layer Deposition of Lanthanum Stabilized Amorphous Hafnium Oxide Thin Films

Abstract

Hafnium dioxide deposited on n-Si(100) by atomic layer deposition (ALD) was incorporated with La2O3 to stabilize the amorphous phase during high-temperature annealing. The incorporation of La was achieved by depositing HfO2 and La2O3 in different ALD cycles that likely produced a HfO2−HfLaxOy periodic structure. X-ray photoelectron spectroscopy compositional analysis shows that the Hf and La atomic percentage ratio can be controlled by varying the Hf and La ALD cycle ratios. Microstructure was determined with X-ray diffraction and cross-sectional transmission electron microscopy. The introduction of La increases the film crystallization temperature from 500 °C for a HfO2 film to 800, 900, and 950 °C for 10 nm films containing 13% La (metal basis), 25% La, and 43% La, respectively. The results indicate that ALD incorporating La is a potential method to grow amorphous HfO2−La2O3 high-κ dielectric thin films.